Switchboard for telephone-lines.



No. 681,743. Patented Sept. 3, |90|. C. E. SCRIBNER & F. R. McBERTY.

SWITCHBUABD FDR TELEPHONE LINES.

(Application tiled Dec. 26, 1899.

(No Model.)

; IWfigeswss:

rrnn STATES PATENT rnicn.

CHARLES E. SCRIBNER, OF CHICAGO, AND FRANK R. MOBERTY, OF EVANS- TON,ILLINOIS, ASSIGNORS TO THE WESTERN ELECTRIC COMPANY, OF

CHICAGO, ILLINOIS.

SWITCHBOARD FOR TELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent No. 681,743, datedSeptember 3, 1901. Application filed December 26, 1899. Serial No.741,564. (No model.)

To aZZ whom it may concern.-

Be it known that we, CHARLES E. SCR'IB- NER, residing at Chicago, andFRANK R. Mo- BERTY, residing at Evanston, in the county of Cook andState of Illinois, citizens of the United States, have invented acertain new and useful Improvement in 'Switchboards for Telephone-Lines,(Cases 481-80,) of which the followingisa full, clear, concise, andexact dero scription.

This invention consists in switching apparatus for unitingtelephone-lines in a telephone-switchboard and for applying to the linesso united current for automatically oper- '15 a'ting signals associatedwith the lines and for supplying the transmitting-telephones at thesubstations of the lines; and it consists in certain automaticappliances for preventing impulses of current in the lines arising fromaccidental contacts between parts of the plugs and spring-jacks used inmaking the connection, such as would produce troublesome noises in thetelephones at the substations.

Switchboards adapted for the automatic control of signals and for thesupply of current from a central source to the telephones at thesubstations are commonly provided with normal branches from the linesleading to the central source of current, including the respectiveindividual line-signals, with electromagnetic switches for severingthese branches when connections are made with the lines, and havetemporarily associated with the lines, through the medium of thecord-cir- 3 5 cuits uniting them in pairs, supervisory signals whichserve to indicate the closed or open condition of the lines at thesubstations, the circuit of the plugs being connected with a source ofcurrent suitable for operating both the signals and the substationtransmittingtelephones. The spring-jacks constituting the terminals inthe switchboard have two contact-pieces for the two line conductors andone or more local contact-pieces for local cir- 5 cuits concerned inoperating the electromagnetic switches and the supervisory signals, andthe plugs for use in these jacks have corresponding contact-piecesarranged in different positions along the axis of the plug, which formthe terminals of line and local-battery circuits, respectively, andwhich thus tend to apply to the various oontactpieces of the spring-jackas the plug is inserted into the jack currents of abnormal amount ordirection, which afiect the telephone of the listening subscriber. Thepresent invention for avoiding these abnormal currents consists in anelectromagnetic switch controlling the connection of the source ofcurrent with the plugcircuit and means for exciting the switch, themeans consisting, first, in a local circuit closed in registeringcontact-pieces of the callingplug and the multiple-jack, and, second, inswitch-contacts in the operators listeningkey which are closed when thetelephone is connected with the plug-circuit, whereby the common sourceof current for exciting the station-transmitters and controlling thesignals may be applied through a plug-circuit temporarily by theoperator in manipulating her listening-key and is applied permanentlyduring a connection automaticallyin the completion of the connection.

The invention is illustrated in the attached drawing, which representsdiagrammatically two telephonelines entering a telephoneswitchboardequipped with our improvement.

The arrangement of apparatus at the sub station is that which is wellknown in telephone sets adapted for the automatic control of signals.The line-circuit is adapted for closure serially through the receivingand transmitting telephones; but the circuit through these instrumentsis normally broken at the telephone-switch, while the call-bell isinterposed in a permanent bridge of the line, together with a condenser,which prevents the passage through this bridge of current from thecentral battery. The line conductors 1 and 2 from this telephoneequipment are led to the line-terminals of spring-jacks a and a in atelephone-switchboard, and they are further extended to the poles of acentral calling-battery b. The actuating-magnet of a self-restoringline-annunciator is connected 5 in the extension of line conductor 2.The con tinuity of both extensions is controlled by an electromagneticswitch or cut-oft relay 0, the actuating-magnet of which is located in aportion 3 of a local circuit of battery, which lo- Ice cal conductorincludes also therestoring-magnet of the line-annunciator. Thespring-jacks and the plugs adapted for use with them may be of the typedescribed in Patent No. 563,333, dated July 7, 1896 while theline-annunciator may be that commonly known as the self-restoring drop,used with branch terminal'switchboards. The plugs adapted for use withthese spring-jacks have, as described in the patent before mentioned,three contactpiecesa tip, a short ring, and a sleevethese beingdesignated in the drawing e, e, and 6 respectively. The contact-pieces eof two plugs fand f, which constitute a pair for uniting two lines, areconnected together by conductors 4 and 5, each of which includes awinding of the repeating-coil g. Similarly contact-sleeves e are unitedby other conductors 6 and 7, which traverse other Windings of the samerepeating coil. At the points of junction of conductors 4 5 and 6 7 ofthe plug-circuit the terminals of a bridgewire 8 are applied. Thisbridge-wire includes the common source of battery for exciting thesubstation -transmitters, which may in practice be the battery I).Supervisory relays h and h are interposed in conductors 6 and 7, theserelays being adapted to control secondary supervisory signals t' and 1'.An operators listening-key 7c is provided for connecting the operatorstelephone 1 into a bridge of the plug-circuit. The conductor 4 of theplug circuit is divided into two branches, each of which is normallyinterrupted. One of the branches is controlled by auxiliaryswitch-contacts k of the operators listening-key. The other iscontrolled by switch-contacts on "m of a special relay m Conductor 5,leading to the tip of plug f, is likewise normally interrupted at otheropen switch-contacts m m of the relay m; but the portion leading to theplug is connected through a resting contact an, forming the terminal ofa tertiary winding of the operators induction-coil Z, which winding isof high resistance. Contact-rings e of the plugs f and f form therespective terminals of two conductors 10 and 11, leading to the batteryI), which are designed to be brought into association with theconductors 3 in the spring-jacks to form complete cir-' cuits therewith.Each of the conductors 10 and 11 includes one of the signal-lampsi andt, and conductor 10 includes a resistancecoil 11.. Asupervisory signalassociated with each supervisory relay h or h is controlled by thisrelay by means of a shunt about the signal traversing theswitch-contacts of the relay. Taking the telephone from its switch foruse at a substation automatically initiates the call, liberating thetarget of the linesignal, and thus calling the attention of theoperator. The attendant responds to the call by inserting ananswering-plug f into a spring-jack a of the line. As the plug is thrustinto the jack the tip makes contact successively with the thimble of thespringjack, with the local contact-spring in the jack, and finallywiththe short line-spring connected with line conductor 1; but none of thesecontacts produces any sound in the telephone of the calling subscriber,since the circuit terminating in the plug is open at the switch-contactsof relay m, both at the listening-key lo and at the relay m. Thering-contact e of a plug also connects momentarily with the thimble ofthe spring-jack, but does not alter the potential of this part, sinceboth contact-pieces are connected with the same pole of battery b.Finally the sleeve 6 makes connection with the thimble at the samemoment that the tip e registers with the short line-spring, whereby theline-circuit is completed. The ring-contact 6 also comes to rest underthe local contact-spring of the jack, closing the local circuit 3 10.The last-mentioned condition results in the excitement of the cut-01frelay 0, which therefore severs the normal extensions of the line,leaving the line disconnected from the battery. The restoring-magnet ofthe line-annunciator is also energized and resets the indicator of theannunciator. The operator now depresses her listening-key, whereby theconductor 4 of the plug-circuit is completed and the battery I) isapplied to the line-circuit for exciting the substation-transmitter.Having learned the order of the calling party for the line called for,the operator tests the line called for in the usual way, obtaining, ifthe line be busy, a click in the telephone, due to the formation ofcurrent from the test-ring through the tertiary winding of theinduction-coil Z. Finding the line free, however, the operator thruststhe plug into the springjack tested. In its progress into the jack thetip of the plug makes contact successively with the thimble, the localspring, and the line-spring; but since the tip is disconnected from theportion of the plug-circuit leading to the telephone of the callingsubscriber the latter is not disturbed by any unnecessary impulses ofcurrent. When the plug reaches its place in the spring-jack, theconductor 7, which is permanently connected with the battery b, isapplied to the line conductor 2. At the same moment the ring e makesconnection with the local spring of the jack, and so effects both thedisconnection of the normal extensions of the line through the agency ofthe cut-off relay of the line and the completion of conductor 5 of theplug-circuit by means of the relay m. The movement of the switches ofthe relay on also closes the bridge in the conductor 4, leading to plugf, in multiple with the circuit closed in the operators listening-key.The operator now disconnects her telephone, breaking the branch ofconductor 4, controlled by the telephone-key; but this act is notattended with any disturbance in the current traversing the line to thecalling subscriber. The listening subscriber hears during thepreliminary work of switching only the single click in thetelephoneproduced by applying a current for exciting the substation-transmitterwhen the operators listening-key is closed. After the completion of theconnection and the calling of the party wanted the response of thelatter closes the line-circuit at the substation called. Afterconnection is thus established between lines supervision is efiected bymeans of signals 2' and e" in the usual way, the lines beingdisconnected when both signals indicate the replacement of thetelephones on the switches at the substations.

We claim as new and desire to secure by Letters Patent 1. Thecombination with a telephone-line and the transmitting-telephone thereofadapted for excitement bycurrent supplied through the line, aspring-jack for the line, and a plug and plug-circuit for makingconnection therewith, of an operators telephone, a listeningkey forconnecting the operators telephone with the plug-circuit, andswitch-contacts associated with said listening-key, controlling theapplication of said source of current to the line; said switch-contactsbeing actuated in connecting the operators telephone to the ri: f)

plug-circuit, and adapted simultaneously to apply to plug-circuitcurrent for exciting the substation transmittingtelephone, substantiallyas described.

2. The combination with telephone-lines, spring-jacks thereof, and ananswering and a calling plug with their associated plug-circuits foruniting lines, of a source of current in a bridge of the plug-circuit,an electromagnetic switch having a pair of switch-contacts interposed inthe plug-circuit at each side of the said bridge containing the sourceof current, a local circuit closed in registering contacts of thecalling-plug and line-jack including the actuating-magnet of saidswitch, an operators'listening-key and auxiliary contacts thereofadapted to effect the closure of the break in the plug-circuit towardthe an swering-plug, substantially as described.

In witness whereof we hereunto subscribe our names this 2d day ofOctober, A. D. 1899.

CHARLES E. SORIBNER. FRANK It. MOBERTY. Witnessesz' ELLA EDLER, FLORENCEE. SUMMnns.

